This invention in general is intended to generate vapor and/or aerosols from a liquid by the application of an electrostatic charge to a porous, semi-conductive, capillament assembly which receives the liquid. More specifically a high voltage DC or AC signal is introduced to a device referred to herein as an "electrostatic wick" or a "vaporizing emitter." This invention has a particular application in the vaporization of essential oils commonly used in the fragrance industry. Essential oils derived from plants, trees, and flowers; also perfumes, natural and synthetic; deodorants, disinfectants, fumigants, fungicides, insecticides, and other liquid substances either water or hydrocarbon based which may be intended to modify, condition, or alter the quality of an indoor or outdoor atmosphere can be vaporized more effectively using such apparatus.
There is a growing concern in the area of indoor air quality often referred to as "sick building syndrome." The modern living and working environment has been designed around energy efficiency and not so oriented around occupant health and comfort. It would be desirable to be able to recreate the properties of fresh outdoor air, indoors. The existence of air ions and their benefit is well documented. Over the last five years there has also been an increased interest in aromatic essences from plants and their application to enhancing or altering the quality of an indoor environment.
The vaporization of aromatic essences and other liquids and also the generation of negative ions is the basis for this invention. The original embodiment of this invention is based upon the need to enhance indoor air quality. This invention can also be modified for applications where it is desirable to generate vapor or aerosols using electrostatic means.
The vaporization of liquids is accomplished by a variety of apparatus and there are also many devices which use electrostatic means to generate aerosols. This invention is specific to the generation of vapor and/or aerosols more efficiently in a range of sizes from a variety of liquids with more control than the prior art, and it can also generate air ions.
The closest prior art was found to be an apparatus for generating a mist of negatively charged liquid aerosols, by Michalchik U.S. Pat. No. 4,776,515. The limitations of the patent based on the claims are that a very specific conductivity of the liquid is required and that charged particles are generated, not a vapor. The device also has specific requirements upon the manner in which the liquid is fed to the capillary in order to maintain the desired aerosol generating effect.
An apparatus for producing a spray of liquid droplets of a specific size range is covered in U.S. Pat. No. 4,829,996. This device is specific to the production of particles by electrostatic means of a certain size and specifically not a vapor. This device is specifically an electrostatic spray generator for an inhaler.
The electrostatic dispersal of liquids by Pollard et al in U.S. Pat. No. 4,400,332 is specific in the use of a porous material having a series of termini which is fed a liquid, namely, petrol fuels. This porous material is charged electrostatically and a spray of fine particles are formed in an air stream. This device produces very fine particles within an air stream wherein an annular enclosure is required. Here again vapor is not mentioned and a moving air stream is required.
Electrostatic enhancement of evaporation by French et al in U.S. Pat. No. 3,771,233 covers a method of specifically improving the evaporation of water from investment cast ceramic molds using an electrostatic charge placed upon the mold. The evaporation process is enhanced with a series of needles of an opposite charge placed near the surface of the mold. This method is specific in claim to the evaporation of water from investment castings. In this case evaporating water is the only objective.
This invention is an improvement upon these methods and others such that both vapor and/or aerosols can be generated from the same device. Another advantage is that the rate of vapor generation can be controlled by the adjustment of the voltage applied to the "emitter," and/or the liquid feed rate and/or the placement of an electrostatic field forming control grid near the emitter. An additional advantage is that various sizes of aerosols can be generated from the same emitter by simple adjustment of these field forming control grids. This invention also will generate air ions of the same polarity as the supply voltage.